Use the correct formula to calculate the circumference of the bend. For example, the formula used when making a 90˚ bend is: Circumference = (pi*2*r) / (360/90). When bending, take into account the ability of the material to bend and sustain the bend. It should also not break during the process or later in application.

How do you calculate the bend radius of a pipe?

If you drew your arc from the inside of your bend, add 1/2 the tube outer diameter to get your true center-line radius. If you drew your arc from the outside (top) of your bend, subtract 1/2 of the tube outer diameter to get your true center-line radius.

How do you calculate the force of bending steel?

In general the bending equation is S = My/I where S is stress (you will use the material's yield stress here), M is the bending moment (force applied times distance from the bend), y is the distance from the neutral axis (in your case this will be half of the bar's thickness) and I is the moment of inertia for the bar ...